All posts tagged models

Models continue to identify numerous regions where tropical cyclones are more likely to form over the next 3-10 days. Multiple tropical waves are predicted to move off Africa. Meanwhile, potentials storm formation near Florida and in the eastern Gulf are indicated in some models. The above analysis includes climate change related features that may influence storm intensity.

The statement publicizes work by two scientists, James Overland and Muyin Wang who have now incorporated three methods of determining when an ice free or nearly ice free Arctic is most likely to manifest. Their work recently published in Geophysical Research Letters and is available there.

Overland notes:

“Rapid Arctic sea ice loss is probably the most visible indicator of global climate change; it leads to shifts in ecosystems and economic access, and potentially impacts weather throughout the northern hemisphere. Increased physical understanding of rapid Arctic climate shifts and improved models are needed that give a more detailed picture and timing of what to expect so we can better prepare and adapt to such changes. Early loss of Arctic sea ice gives immediacy to the issue of climate change.”

Wang adds:

“There is no one perfect way to predict summer sea ice loss in the Arctic. So we looked at three approaches that result in widely different dates, but all three suggest nearly sea ice-free summers in the Arctic before the middle of this century.”

The three approaches Wang and Overland incorporated:

1. A trends analysis that predicts nearly ice free conditions by around 2020. This analysis takes into account past average rates of sea ice loss and extrapolates it forward in time. The analysis Wang and Overland put together establish a nearly ice free state by 2020.

2. A stochastic approach that incorporates a higher natural variability with large, somewhat random, melt events resulting in a near ice-free state by or before 2030.

3. A model approach which still shows nearly ice free summers occurring during a period between 2040 to 2080.

Wang and Overland note that the model predictions are likely to be much slower than actual melt. That said, they defended the models saying it was necessary to continue their development in order to better understand the Arctic climate.

Overall, this represents a rapid shift on the part of NOAA. Past official estimates were for near ice free conditions being most likely after the first half of the 21rst century. But with rapid melt trends pushing for a much sooner melt date, NOAA has adjusted its forecast. Given this most recent paper, Wang and Overland seem to indicate a most likely near ice free state in a time period of 2020-2050.

NOAA’s Predictions in Context

It is my opinion that the range NOAA gives of between 2020 to 2050, with caveats that model predictions are likely to be too slow, is still a bit too conservative in that it fails to give warning to the rising risk of an almost immediate melt. Just following current melt trends brings us to a completely ice-free Arctic by 2017. Any single melt year like 2007 or 2010 (volume) brings us to an ice free or nearly ice free state in one year.

Perhaps NOAA could add another set of circumstances to its analysis — the exponential melt trend analysis. Such a trend would incorporate the risk of a near immediate melt, warn the public and governments of the potential for such an event and give NOAA a more realistic near ice free range of 2015-2050.

In doing this, NOAA would acknowledge the potential for an ice-free or nearly ice-free state within the current decade. This acknowledgement is important from the standpoint of emergency preparedness. An ice free Arctic and the likely climate mayhem it would produce is not something we generally want to remain unaware of.

Risk assessment forecasts provided at this blog and incorporating sea ice volume data from PIOMAS show a 10% chance of an ice free or nearly ice free state this year, with a high risk (60% chance) of an ice free state by 2017. Some polar experts like Peter Wadhams believe that the Arctic will reach an ice-free state as soon as 2015-2016. Wadhams has spent thousands of hours researching the ice aboard navy submarines. So if there’s someone who knows sea ice, it’s Wadhams.

While negative feedbacks that slow the loss of sea ice may emerge, any prediction for a near ice free state after 2020 hangs its hopes on those, yet to emerge, melt inhibitors. More likely, the reduced resilience of the ice will compound with a warming climate to push melt to occur with a bang and not a long, drawn-out whimper. Further, the fact that the ocean upon which the ice rests is collecting a greater volume of human produced warming is likely to enhance bottom melt regardless of atmospheric temperatures, even in winter time. We can see this in the catastrophic volume losses observed even during the coldest months with current peak volumes comparable to those of the warmer months during the 1980s.

If current volume trends bear out, we see ice free winter states by 2040. Something neither the models, nor NOAA have on their public radar.

What is happening in the Arctic currently constitutes the beginning of a global climate and weather emergency. The UK Met recently called an emergency meeting due to a rapid shifting in the UK climate as a result of catastrophic sea ice melt. Such emergency sessions are likely to become more common as time goes forward. NOAA’s movement on this matter does represent an increased alertness to the scope of the problem and should be applauded. The work of their scientists and modelers has enabled a greater understanding of the Arctic than ever before. However, for scientists to remain on the cutting edge, they will have to adjust to events far more rapidly than in the past. They will also need to begin to acknowledge the potential for dangerous outlier events.

The current NOAA statement strikes a balance between the traditional conservatism of science and the need to acknowledge an Arctic undergoing catastrophic change far more rapidly than anyone expected. Thus, it represents progress. That said, if current trends bear out, these still somewhat conservative predictions of near ice free conditions via NOAA may soon be moot.